Tool retainer



Mgy 16, 1939. E. B. LEAR TOOL RETAINER Filed April 3, 1937 INVENTOR /PL ima Patented May 16, 1939 UNirEo sa TOOL RETAINER Earl B. Lear, Detroit, Mich.,

assigner to Chicago i Pneumatic Tool Company, New York, N. Y., a corporation of NewJersey Application April 3, 1937, Serial No. l34,716

2 Claims.

This invention relates to retainers for percussive tools and more particularly to a retainer for preventing a drill steel from becoming accidentally detached from the iront head oi a rock drill in which it is supported.

Among the objects of the invention are the provision oi improved means for effectively holding the retainer in .adjusted position; the employment of resilient means for mounting the retainer on the iront head of a rock drill; and the provision of a device which is simple in construction and inexpensive to manufacture. An important feature of the invention resides in a renewable bushing seated in a non-circular socket in the side of the iront head, said bushing being arranged to receive one of the trunnions which carry the retainer, and being adapted to cooperate with the trunnion to yieldingly lock the latter in adjusted position.

Other objects and features of the invention will be more clearly pointed out in the following description and appended claims.

In the accompanying drawing which illustrates one embodiment of the invention:

Fig. l is a front view partly in elevation and partly in section ci a fragmentary portion of a rock drill embodying the invention;

Fig. 2 is a side elevation, looking from right to left in Fig. 1;

Fig. 3 is a cross section looking upwardly, as indicated by the arrows 3 in Fig. 1;

Fig. 4 is a side elevation showing a fragmentary portion of one of the bushings seated in a socket in the side oi the vfront head;

Fig. 5 is a perspective view ci the bushing shown in Fig. 4;

Fig. 6 is a side elevational view of one of the trunnions;

Fig. '7 is a front elevational view of said trunnion; and

Fig. 8 is a plan View of the trunnon.

Figs. 4 to 8 inclusive are drawn on a larger scale than Figs. 1, 2 and 3. Referring particularly to Fig. l, a drill steel Ill is provided with a collar II engaging the lower end of a chuck I2 mounted in a bore i3 in the front head I4 of a rock drill. Shank I5 of the steel is oi polygonal cross-section and has a sliding fit with the chuck. The upper end of the shank is adapted to receive blows delivered by a piston extension IB. The structure described up to this point is conventional.

In accordance with the present invention, the iront head I4 has a pair oi aligned transverse bores I8 extending inwardly from a pair of bosses (C1. Mil-19.1)

I9 at opposite sides of the iront head. Each bore it provides a socket for receiving a trunnion bushing 2U. The bushing has al hollow stem 2l which fits the bore I8 and a flange 22 which seats against a dat surface on boss I9. The bushings 5 it .are held in their respective sockets by a press iit and are adapted to be removed and replaced after they have become worn. In order to prevent the bushing from turning, anges 22 are provided with non-circular or flattened portions 2id adapted to seat on lugs' 23 projecting from and integral with the iront head.

The bushings 2d support a pair of trunnions 243. As shown in Figs. 6, and 8, each trunnion has a pivot portion 25 and a head 2t, the head 15 having a bore 21. The pivots 25 are mounted to-turn in bores 28 in the bushings. The heads 2t are yieldingly held, by means to be described presently, in engagement with the outer faces of the anges 22 on the bushings. As shown in Figs. 6 and 7, the abutting face of the head 26 is generally flat but is provided with radially extending grooves 29. These grooves cooperate with ribs or projections 3G on the outside face of the bushing flange 22. n the illustrative em- 2 bodiment of the invention, there are three sets oi grooves on each trunnion, any one set of which may register with the bushing ribs and thereby yieldingly lock the trunnions in any one of three different positions of adjustment. 30

A resilient tool retainer 32 has a yoke portion 33 oi ordinary construction adapted to underlie the collar Ii on the drill steel I and a pair of upstanding substantially parallel arms 3d. The arms 34 have cylindrical extensions 35 slidingly 35 fitting the trunnion bores 21 and have collars 3G seating against the lower ends of the trunnions. The upper extremities of the arms 34 are provided with removable means such as nuts 3l. Compression springs 33 surround the extensions 40 35 and abut against the nuts 31 to support the retainer in its uppermost position with the collars 36 seated on the trunnions. The retainer 32 is so constructed that the arms 34 are under tension when connected to the trunnions 2li and tend to 45 i`orce the trunnions toward each other.

in operation, the piston I6 delivers a succession of impacts to the drill steel I and, under certain conditions, the collar Ii of the drill steel may strike against the yoke portion 33 of the retainer 50 32. Springs 38 act as a shock absorber by per- Initting the retainer to yield in the direction of the impacts. This minimizes wear on the iront head and prolongs the life of the retainer. The retainer 32 is normally held in the position shown 55 in full lines in Fig. 2. When it is desired to change drill steels, the retainer is swung to the broken line position. Movement away from its adjusted position is resisted by the pressure of the grooved trunnions 24 against the projections 3U on the stationary bushings 20 caused by the resiliency of the retainer arms. As the retainer is swung, the projection 3i] rst cams the trunnions 24 apart, thereby increasing the tension of the retainer arms, and later permits the trunnions to snap back when a different set of grooves 29 becomes -aligned with the projections 3B. Preferably, though not necessarily, the construction of the bushings and trunnions is identical on both sides of the front head.

It will be apparent to those skilled in the art that various changes and adaptations of the illustrative embodiment of the invention may be resorted to without departing from the spirit of the invention. For example, the cam arrangement between the bushings and trunnions may be reversed so that the grooves are formed on the bushings and the projections are carried by the trunnions. Furthermore, the front head referred to in the specification and claims need not necessarily be in one piece but may comprise several parts carried by the cylinder either in fixed relation or so connected relative thereto as to accomplish the results obtained by the illustrative embodiment of the invention.

What is claimed is:

1. A rock drill comprising a front head and a collared drill steel supported therein, a retainer having a yoke portion adapted to underlie the coll-ar and having resilient arms extending upwardly therefrom along the sides of the front head, said front head having a pair of diametrically opposed transverse bores extending inwardly from opposite sides of the front head, each arm of the retainer being carried by a trunnion, each and retainer about the trunnion axis, said means comprising a groove or depression formed on the inner face of one of the trunnion heads and extending outwardly from the pivot portion, and a complementary rib aftixed to and projecting outwardly from the front head and positioned to register with said groove, said resilient retainer arms being arranged to urge said trunnions tward each other and thereby yieldingly hold the groove and rib in registry.

2. A rock drill comprising a front head and a collared drill steel supported therein, a retainer having a yoke portion normally underlying the collar and having arms extending upwardly on opposite sides of the front head, said front head having bosses on its opposite sides and h-aving a pair of transverse bores extending inwardly from said bosses, a pair of renewable bushings mounted in said bores and held therein by a press t, each bushing having an integral ange seated on the associated boss, a pair of axially alined trunnions having integral pivot portions mounted to turn in said bushings and removable from the front head by movement away from each other, each bushing ilange being disposed to surround the associated pivot portion, each trunnion having a longitudinal bore in line with and receiving an arm of the retainer, whereby said retainer normally prevents removal of the trunnions from the fron't head, said arms being shaped to fit the trunnion bores, removable members secured to the free ends of the arms, springs between said members and the trunnions, and means yieldingly resisting rocking movement of the trunnions and arms away from the normal position, said means comprising a cam surface formed on one of the trunnions and a complementary cam clement formed on the outside face of the ange on the hold said cam surface in engagement with said cam element, said front head, drill steel, arms, trunnion bores, pivot portions and bushings all being mounted on axes in the same plane.

EARL B. LEAR. 

